The present invention relates to apparatus and methods for implanting ocular implants in eyes. More particularly, the invention relates to such apparatus and methods for implanting, for example, delivering, placing, positioning and the like, particulate ocular implants in an eye, for example, at one or more of various locations in an eye, for example, a mammalian eye.
The mammalian eye is a complex organ comprising an outer covering including the sclera (the tough white portion of the exterior of the eye) and the cornea (the clear outer portion covering the pupil and iris). In a medial cross section, from anterior to posterior, the eye comprises features including, without limitation: the cornea, the anterior chamber (a hollow feature filled with a watery, clear fluid called the aqueous humor and bounded by the cornea in the front and the lens in the posterior direction), the iris (a curtain-like feature that can open and close in response to ambient light), the lens, the posterior chamber (filled with a viscous fluid called the vitreous humor), the retina (the innermost coating of the back of the eye and comprising light-sensitive neurons), the choroid (an intermediate layer providing blood vessels to the cells of the eye), and the sclera. The posterior chamber comprises approximately ⅔ of the inner volume of the eye, while the anterior chamber and its associated features (lens, iris etc.) comprise about ⅓ of the eye's inner volume.
Ocular implants containing one or more therapeutic components combined with matrix components, such as polymeric components, have been proposed for use, for example, to treat conditions/diseases of the eye. Such implants have been suggested for use at various locations in the eye, for example, in the vitreous, subconjunctivally, anterior chamber and posterior chamber of the eye.
Although such prior art implants have taken on various shapes, forms and configurations, one very useful implant form is a plurality of variously sized microparticles, e.g., microspheres and the like. For example, intravitreal injection of conventional particles, which average about 1-100 microns in size, is known and has been previously practiced. This injection of such microparticles is usually conducted using the microparticles suspended in a liquid aqueous medium. It would be advantageous to deliver the microparticles in the eye without such a liquid carrier medium.
Dry delivery in the eye of extruded, rod shaped implants, for example having diameters of about 450 microns and lengths of 3-6 millimeters, has been successfully accomplished. However, it would be highly desirable to reduce the diameter of the implant in order to allow the use of a smaller needle for injection. Reducing the diameter of such rod shaped implants often reduces the strength of the implant so that it breaks up during handling. Moreover, as such a rod shaped implant is reduced in diameter, the length of the implant gets much longer (so as to deliver an equal amount of therapeutic component to the eye) making the implant impractical for use, and even a hazard for ocular injection.
Prior attempts to dry inject microparticles in the eye have been less than completely successful. For example, without a liquid or gel carrier in the lumen containing the microparticles, the microparticles tend to become wedged between the injector assembly and the inner wall of the needle, thus preventing the assembly from delivering the full implant to the eye or causing the physician to apply excessive amounts of force to the assembly, which excessive force can be dangerous to the eye.
There continues to be a need for apparatus and methods effective to dry implant microparticles in an eye utilizing a liquid free lumen.